Front feet

Merlin has a sore on the top of his left front foot. The vet thinks he is hitting it on the stairs or the curb- maybe so, but I never see it. Or maybe it is on the dog door, I didn't think of that. I may have to put boots on the front but I can't see him leaving them on. He was much more cooperative at the vet's than he was as a puppy when he would scream and holler if they as much as touched him. I had them muzzle him up until about three years ago as I didn't want him to bite anyone. But today he was very good except when he was barking for food.